【０００４】
【発明が解決しようとする課題】
従来の真空浸炭炉による浸炭では、炉殻内に浸炭ガスが充満する量の浸炭ガスを導入するが、実際に必要な浸炭ガスはワークの周辺だけであり、その他の場所では本来必要ないのにもかかわらず、従来の真空浸炭炉による浸炭では、断熱材で囲まれた断熱浸炭室内及び断熱浸炭室を取り囲む真空に耐える炉殻内すべてに浸炭ガスを導入し充満させていた。浸炭ガスとしては炭化水素系のガスを使用するが、一般に単価が高く、浸炭されない浸炭ガスは大気中に放出され資源の無駄となった。さらに従来の真空浸炭炉による浸炭では、炭化水素系ガスを例えば約１０Kpの減圧下で約１０００°Ｃといった高温下で真空ポンプで排気したとき、約１０００°Ｃから約４００°Ｃに至る温度範囲でスーチングがみられ、浸炭室の断熱性材料外側部分では約２００°Ｃで断熱性材料が多孔質のため断熱性材料に浸透した浸炭ガスによるスーチングがみられることが知られている。[0004]
[Problems to be solved by the invention]
In carburization with a conventional vacuum carburizing furnace, carburizing gas is introduced into the furnace shell in an amount sufficient to be filled with carburizing gas, but actually the necessary carburizing gas is only at the periphery of the work, and it is not necessary at other places. Nevertheless, in the carburization by the conventional vacuum carburizing furnace, the carburizing gas is introduced and filled in all of the inside of the furnace case which is surrounded by the heat insulating material and the inside of the furnace shell which withstands the vacuum surrounding the heat insulation carburizing chamber. Although a hydrocarbon gas is used as the carburizing gas, the unit price is generally high, and the carburizing gas which is not carburized is released to the atmosphere, which is a waste of resources. Furthermore, in the case of carburizing in a conventional vacuum carburizing furnace, the temperature range from about 1000 ° C. to about 400 ° C. when the hydrocarbon gas is evacuated by a vacuum pump at a high temperature of about 1000 ° C. under a reduced pressure of about 10 Kp, for example. It is known that the sooting is observed, and that the heat insulating material is porous at about 200 ° C. in the heat insulating material outer part of the carburizing chamber, so that the sooting by the carburizing gas infiltrated into the heat insulating material is observed.
【０００７】
【発明の効果】
かかる構成により、浸炭室の断熱材で囲まれた断熱浸炭室内にのみ浸炭ガスを導入し、断熱浸炭室と炉殻との間の空間には安価な水素及び窒素を含む浸炭ガス以外のガスを導入することをようにしたので、必要最小限の浸炭ガスによる浸炭ができる真空浸炭の浸炭ガス縮減方法を提供するものとなり、ランニングコストを低減し、資源の無駄をなくすものとなった。[0007]
【Effect of the invention】
With this configuration, only the heat insulating carburizing chamber surrounded by insulation carburizing chamber by introducing a carburizing gas, a gas other than the carburizing gas in the space containing inexpensive hydrogen and nitrogen between the insulation carburizing chamber and furnace shell The introduction of this method provides a method for reducing carburizing gas in vacuum carburization that can be carburized with the minimum necessary carburizing gas, thereby reducing running costs and eliminating waste of resources.
【０００８】
好ましくは、前記断熱材を２層構成にし、内側断熱材は真空圧縮成形した緻密な材質のセラミックファイバーとし、外側断熱材は多孔質のセラミックファイバーとし、前記内側断熱材と外側断熱材との間に金属薄板又はガスが浸透しない薄膜を張りつけたことにより、浸炭ガスが浸透しない金属薄板又は薄膜と、内側断熱材は浸炭ガスが浸透しにくい真空圧縮成形した緻密な材質のセラミックファイバーを使用したことにより、外側断熱材には浸炭ガスが浸透することはなく、内側断熱材は浸炭ガスが浸透しにくいので、浸炭ガスの浸透を防止し、スーチングを減少させた真空浸炭の浸炭ガス縮減方法を提供するものとなり、かつ断熱材を内側断熱材のみ高価な真空圧縮成形した緻密な材質のセラミックファイバーとしたことにより、安価な真空浸炭炉を提供するものとなった。さらに好ましくは前記浸炭ガス以外のガスの圧力を、前記浸炭ガスの圧力より僅かに高くしたので、浸炭ガスは内側断熱材内部から漏れることなく炉殻下方の排出口より排気されるものとなり、さらにスーチングを減少させたものとなった。[0008]
Preferably, the heat insulating material has a two-layer structure, the inner heat insulating material is a vacuum compression molded compacted ceramic fiber, the outer heat insulating material is a porous ceramic fiber, and the space between the inner heat insulating material and the outer heat insulating material By attaching a thin metal plate or thin film to which gas does not penetrate, a thin metal plate or thin film to which carburizing gas does not penetrate As a result, no carburizing gas penetrates the outer heat insulating material, and the inner heat insulating material hardly penetrates the carburizing gas, thus preventing permeation of the carburizing gas and providing a method for reducing carburizing gas in vacuum carburization with reduced sooting. Cost-effective because the heat insulation material is a dense ceramic fiber with only the inner heat insulation material made by expensive vacuum compression molding. It was the one that provides an empty carburizing furnace. Further preferably the pressure of the gas other than the carburizing gas, since the slightly higher than the pressure of the carburizing gas, carburizing gas becomes what is exhausted from the outlet of the furnace shell lower without leaking from inside the inner insulation, further It is the one with reduced sewing.
【０００９】
【発明の実施の形態】
図１は本発明の実施の形態に使用される連続真空浸炭炉の立面概念ブロック図を示し、図２は図１のＡ−Ａ線に沿ったＡ矢視方向概略断面図で、本発明の実施の形態の浸炭ガスの流れを示す概略断面図である。本発明の実施の形態に使用される真空浸炭炉は合金部品用の連続真空浸炭炉２０であり、装入室１とそれぞれ真空シール扉１２で仕切られた独立した、昇温室２、断熱材７で囲まれた断熱浸炭室である浸炭拡散室３（浸炭室と拡散室とで構成されてもよい）、降温室４、焼入室５及び搬出室６を有する。１１は被処理物であるワーク、１０は昇降コンベア、１３は装入扉、１４は搬出扉である。ワーク１１は装入室１から装入され、昇温室２で例えば約０、５Kpの減圧下で約１０００°Ｃといった温度まで加熱された後、浸炭拡散室３に入る。浸炭拡散室３では浸炭ガスを導入し例えば約１０Kpの減圧下で約１０００°Ｃといった温度で浸炭を行い、その後で浸炭ガスを吸引・放出し、例えば約０、５Kpの減圧下で約１０００°Ｃといった温度で拡散を行い、ワーク１１はその後降温室４で所定の焼入温度まで降温・保持され、次の焼入室５及び搬出室６を通り搬出される。[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an elevation conceptual block diagram of a continuous vacuum carburizing furnace used in the embodiment of the present invention, and FIG. 2 is a schematic sectional view taken along line A-A of FIG. It is a schematic sectional drawing which shows the flow of carburizing gas of embodiment of. The vacuum carburizing furnace used in the embodiment of the present invention is a continuous vacuum carburizing furnace 20 for alloy parts, which is an independent heating chamber 2 and a heat insulating material 7 separated from the charging chamber 1 and the vacuum sealing door 12 respectively. It has a carburizing diffusion chamber 3 (which may be constituted by a carburizing chamber and a diffusion chamber) which is an adiabatic carburizing chamber surrounded by the above, a temperature lowering chamber 4, a quenching chamber 5 and an unloading chamber 6. 11 is a workpiece which is an object to be processed, 10 is a lift conveyor, 13 is a loading door, and 14 is a unloading door. The work 11 is charged from the charging chamber 1 and heated to a temperature of about 1000 ° C. under a reduced pressure of, for example, about 0, 5 Kp in the heating chamber 2 and then enters the carburizing diffusion chamber 3. In the carburizing diffusion chamber 3, carburizing gas is introduced and carburized at a temperature of about 1000 ° C. under a reduced pressure of about 10 Kp, for example, and thereafter the carburizing gas is sucked and released, for example about 1000 ° under a reduced pressure of about 0, 5 Kp. Diffusion is performed at a temperature such as C, and the work 11 is then cooled and held to a predetermined quenching temperature in the cooling chamber 4, and is carried out through the next quenching chamber 5 and the unloading chamber 6.
【００１１】
本発明の実施の形態の真空浸炭の浸炭ガス縮減方法は、断熱材７で囲まれた断熱浸炭室である浸炭拡散室３を有する真空浸炭炉２０に於いて、浸炭工程の間は浸炭拡散室３内にのみ浸炭ガスを、上方浸炭ガス導入ノズル２３及び横方向浸炭ガス導入ノズル２４から導入し、同時に水素又は窒素を含む（水素及び窒素の混合ガスでもよい）浸炭ガス以外のガスを、熱浸炭室３を取り囲む炉殻１５と浸炭拡散室との間の空間３２に上方ガス導入ノズル２５及び横方向ガス導入ノズル２６から導入し充満するようにした。浸炭ガス以外のガスは、水素又は窒素を含む安価な入手し易いガスである。上方浸炭ガス導入ノズル２３及び横方向浸炭ガス導入ノズル２４から浸炭拡散室３内に導入された浸炭ガスは、矢印で示すように浸炭拡散室を通り、浸炭拡散室の底部炉壁の孔３０から炉殻１５と浸炭拡散室との間の空間３２を通り、炉殻１５下方の下方ガス排出口３１から図示しない真空ポンプで吸引されて排出される。水素又は窒素を含む浸炭ガス以外のガスも炉殻１５と浸炭拡散室との間の空間３２を通り、浸炭ガスと同様に、炉殻１５下方の下方ガス排出口３１から図示しない真空ポンプで吸引されて排出される。[0011]
The method for reducing carburizing gas of vacuum carburization according to the embodiment of the present invention comprises a carburizing diffusion chamber between carburizing steps in a vacuum carburizing furnace 20 having a carburizing diffusion chamber 3 which is an adiabatic carburizing chamber surrounded by a heat insulating material 7. The carburizing gas is introduced from only the upper carburizing gas introducing nozzle 23 and the lateral carburizing gas introducing nozzle 24 only at the same time, and at the same time, a gas other than the carburizing gas containing hydrogen or nitrogen (or a mixed gas of hydrogen and nitrogen) may be The space 32 between the furnace shell 15 surrounding the carburizing chamber 3 and the carburizing diffusion chamber is introduced from the upper gas introducing nozzle 25 and the lateral gas introducing nozzle 26 so as to be filled. Gases other than the carburizing gas are inexpensive and easily accessible gases including hydrogen or nitrogen. The carburizing gas introduced into the carburizing diffusion chamber 3 from the upper carburizing gas introducing nozzle 23 and the lateral carburizing gas introducing nozzle 24 passes through the carburizing diffusion chamber as shown by the arrows and from the hole 30 in the bottom furnace wall of the carburizing diffusion chamber The gas passes through a space 32 between the furnace shell 15 and the carburizing diffusion chamber, and is sucked and discharged by a vacuum pump (not shown) from a lower gas outlet 31 below the furnace shell 15. Gases other than the carburizing gas containing hydrogen or nitrogen also pass through the space 32 between the furnace shell 15 and the carburizing diffusion chamber, and are sucked by a vacuum pump (not shown) from the lower gas outlet 31 below the furnace shell 15 similarly to the carburizing gas. Being discharged.
【００１３】
図３は図２の概略断面図とは異なる本発明の実施の形態の浸炭ガスの流れを示す概略断面図で、図２の断熱材を２層構成にし、内側断熱材７１は真空圧縮成形した緻密な材質のセラミックファイバーとし、外側断熱材７２は多孔質のセラミックファイバーとし、内側断熱材７１と外側断熱材７２との間に金属薄板又はガスが浸透しない薄膜７３を張りつけたことにより、浸炭ガスが浸透しない金属薄板又は薄膜７３を使用したので、外側断熱材７２には浸炭ガス以外のガスが導入されるので浸炭ガスが浸透することはなく、内側断熱材７１は浸炭ガスが浸透しにくい真空圧縮成形した緻密な材質のセラミックファイバーとしたことにより、断熱材内部への浸炭ガスの浸透を防止し、浸炭室の断熱性材料外側部分では約２００°Ｃといった温度領域であっても外側断熱材７２には浸炭ガスが浸透することはなく、スーチングを減少させた真空浸炭の浸炭ガス縮減方法を提供するものとなり、かつ断熱材を内側断熱材７１のみ高価な真空圧縮成形した緻密な材質のセラミックファイバーとしたことにより、安価な真空浸炭炉を提供するものとなった。さらに図２、図３の実施の形態では、浸炭ガス以外のガスの圧力を約１２Kpとし、浸炭ガスの圧力約１０Kpより僅かに高くしたので、浸炭ガスは内側断熱材７１内部から漏れることなく炉殻１５下方の下方ガス排出口３１より排気されるものとなり、さらにスーチングを減少させたものとなった。[0013]
FIG. 3 is a schematic cross sectional view showing the flow of carburizing gas according to an embodiment of the present invention different from the schematic cross sectional view of FIG. 2, in which the heat insulating material of FIG. The outer heat insulating material 72 is a porous ceramic fiber, and a thin metal plate or a thin film 73 to which gas does not penetrate is attached between the inner heat insulating material 71 and the outer heat insulating material 72 to form a carburizing gas. Since a sheet other than the carburizing gas is introduced to the outer heat insulating material 72, the inner heat insulating material 71 does not permeate the carburizing gas, and the inner heat insulating material 71 is a vacuum which is hard to permeate the carburizing gas. By using a compact ceramic fiber made of compression molded material, penetration of carburizing gas into the inside of the heat insulating material is prevented, and the temperature of about 200 ° C in the heat insulating material outer part of the carburizing chamber Even in this region, no carburizing gas penetrates the outer heat insulating material 72, providing a carburizing gas reduction method for vacuum carburizing with reduced stitching, and the heat insulating material is an expensive vacuum only for the inner heat insulating material 71. By using a compact ceramic fiber made by compression molding, an inexpensive vacuum carburizing furnace is provided. Furthermore, FIG. 2, in the embodiment of FIG. 3, the pressure of the gas other than the carburizing gas to about 12 kp, since the slightly higher than the pressure about 10Kp carburizing gas, the furnace without carburizing gas leaking from inside the inner insulation material 71 The gas is exhausted from the lower gas discharge port 31 below the shell 15 and the sewing is further reduced.